1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
2 config CC_VERSION_TEXT !! 2 config DEFCONFIG_LIST
3 string 3 string
4 default "$(CC_VERSION_TEXT)" !! 4 depends on !UML
5 help !! 5 option defconfig_list
6 This is used in unclear ways: !! 6 default "/lib/modules/$(shell,uname -r)/.config"
7 !! 7 default "/etc/kernel-config"
8 - Re-run Kconfig when the compiler i !! 8 default "/boot/config-$(shell,uname -r)"
9 The 'default' property references !! 9 default ARCH_DEFCONFIG
10 CC_VERSION_TEXT so it is recorded !! 10 default "arch/$(ARCH)/defconfig"
11 When the compiler is updated, Kcon <<
12 <<
13 - Ensure full rebuild when the compi <<
14 include/linux/compiler-version.h c <<
15 line so fixdep adds include/config <<
16 auto-generated dependency. When th <<
17 will touch it and then every file <<
18 11
19 config CC_IS_GCC 12 config CC_IS_GCC
20 def_bool $(success,test "$(cc-name)" = !! 13 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
21 14
22 config GCC_VERSION 15 config GCC_VERSION
23 int 16 int
24 default $(cc-version) if CC_IS_GCC !! 17 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
25 default 0 18 default 0
26 19
27 config CC_IS_CLANG 20 config CC_IS_CLANG
28 def_bool $(success,test "$(cc-name)" = !! 21 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
29 22
30 config CLANG_VERSION 23 config CLANG_VERSION
31 int 24 int
32 default $(cc-version) if CC_IS_CLANG !! 25 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
33 default 0 <<
34 <<
35 config AS_IS_GNU <<
36 def_bool $(success,test "$(as-name)" = <<
37 <<
38 config AS_IS_LLVM <<
39 def_bool $(success,test "$(as-name)" = <<
40 <<
41 config AS_VERSION <<
42 int <<
43 # Use clang version if this is the int <<
44 default CLANG_VERSION if AS_IS_LLVM <<
45 default $(as-version) <<
46 <<
47 config LD_IS_BFD <<
48 def_bool $(success,test "$(ld-name)" = <<
49 <<
50 config LD_VERSION <<
51 int <<
52 default $(ld-version) if LD_IS_BFD <<
53 default 0 <<
54 <<
55 config LD_IS_LLD <<
56 def_bool $(success,test "$(ld-name)" = <<
57 <<
58 config LLD_VERSION <<
59 int <<
60 default $(ld-version) if LD_IS_LLD <<
61 default 0 <<
62 26
63 config RUSTC_VERSION !! 27 config CC_HAS_ASM_GOTO
64 int !! 28 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 29
70 config RUST_IS_AVAILABLE !! 30 config CC_HAS_WARN_MAYBE_UNINITIALIZED
71 def_bool $(success,$(srctree)/scripts/ !! 31 def_bool $(cc-option,-Wmaybe-uninitialized)
72 help 32 help
73 This shows whether a suitable Rust t !! 33 GCC >= 4.7 supports this option.
74 <<
75 Please see Documentation/rust/quick- <<
76 to satisfy the build requirements of <<
77 <<
78 In particular, the Makefile target ' <<
79 why the Rust toolchain is not being <<
80 <<
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 <<
85 config CC_CAN_LINK <<
86 bool <<
87 default $(success,$(srctree)/scripts/c <<
88 default $(success,$(srctree)/scripts/c <<
89 <<
90 config CC_CAN_LINK_STATIC <<
91 bool <<
92 default $(success,$(srctree)/scripts/c <<
93 default $(success,$(srctree)/scripts/c <<
94 34
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 !! 35 config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id <<
97 config GCC_ASM_GOTO_OUTPUT_BROKEN <<
98 bool 36 bool
99 depends on CC_IS_GCC !! 37 depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
100 default y if GCC_VERSION < 110500 !! 38 default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9
101 default y if GCC_VERSION >= 120000 && !! 39 help
102 default y if GCC_VERSION >= 130000 && !! 40 GCC's -Wmaybe-uninitialized is not reliable by definition.
103 !! 41 Lots of false positive warnings are produced in some cases.
104 config CC_HAS_ASM_GOTO_OUTPUT <<
105 def_bool y <<
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN <<
107 depends on $(success,echo 'int foo(int <<
108 <<
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT <<
110 depends on CC_HAS_ASM_GOTO_OUTPUT <<
111 # Detect buggy gcc and clang, fixed in <<
112 def_bool $(success,echo 'int foo(int * <<
113 <<
114 config TOOLS_SUPPORT_RELR <<
115 def_bool $(success,env "CC=$(CC)" "LD= <<
116 <<
117 config CC_HAS_ASM_INLINE <<
118 def_bool $(success,echo 'void foo(void <<
119 <<
120 config CC_HAS_NO_PROFILE_FN_ATTR <<
121 def_bool $(success,echo '__attribute__ <<
122 42
123 config PAHOLE_VERSION !! 43 If this option is enabled, -Wno-maybe-uninitialzed is passed
124 int !! 44 to the compiler to suppress maybe-uninitialized warnings.
125 default $(shell,$(srctree)/scripts/pah <<
126 45
127 config CONSTRUCTORS 46 config CONSTRUCTORS
128 bool 47 bool
>> 48 depends on !UML
129 49
130 config IRQ_WORK 50 config IRQ_WORK
131 def_bool y if SMP !! 51 bool
132 52
133 config BUILDTIME_TABLE_SORT !! 53 config BUILDTIME_EXTABLE_SORT
134 bool 54 bool
135 55
136 config THREAD_INFO_IN_TASK 56 config THREAD_INFO_IN_TASK
137 bool 57 bool
138 help 58 help
139 Select this to move thread_info off 59 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 60 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 61 except flags and fix any runtime bugs.
142 62
143 One subtle change that will be neede 63 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 64 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 65
146 menu "General setup" 66 menu "General setup"
147 67
148 config BROKEN 68 config BROKEN
149 bool 69 bool
150 70
151 config BROKEN_ON_SMP 71 config BROKEN_ON_SMP
152 bool 72 bool
153 depends on BROKEN || !SMP 73 depends on BROKEN || !SMP
154 default y 74 default y
155 75
156 config INIT_ENV_ARG_LIMIT 76 config INIT_ENV_ARG_LIMIT
157 int 77 int
158 default 32 if !UML 78 default 32 if !UML
159 default 128 if UML 79 default 128 if UML
160 help 80 help
161 Maximum of each of the number of arg 81 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 82 variables passed to init from the kernel command line.
163 83
164 config COMPILE_TEST 84 config COMPILE_TEST
165 bool "Compile also drivers which will 85 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM !! 86 depends on !UML
>> 87 default n
167 help 88 help
168 Some drivers can be compiled on a di 89 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 90 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 91 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 92 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 93 drivers to compile-test them.
173 94
174 If you are a developer and want to b 95 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 96 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 97 drivers to be distributed.
177 98
178 config WERROR <<
179 bool "Compile the kernel with warnings <<
180 default COMPILE_TEST <<
181 help <<
182 A kernel build should not cause any <<
183 enables the '-Werror' (for C) and '- <<
184 to enforce that rule by default. Cer <<
185 such as the linker may be upgraded t <<
186 well. <<
187 <<
188 However, if you have a new (or very <<
189 and unusual warnings, or you have so <<
190 you may need to disable this config <<
191 successfully build the kernel. <<
192 <<
193 If in doubt, say Y. <<
194 <<
195 config UAPI_HEADER_TEST <<
196 bool "Compile test UAPI headers" <<
197 depends on HEADERS_INSTALL && CC_CAN_L <<
198 help <<
199 Compile test headers exported to use <<
200 self-contained, i.e. compilable as s <<
201 <<
202 If you are a developer or tester and <<
203 headers are self-contained, say Y he <<
204 <<
205 config LOCALVERSION 99 config LOCALVERSION
206 string "Local version - append to kern 100 string "Local version - append to kernel release"
207 help 101 help
208 Append an extra string to the end of 102 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 103 This will show up when you type uname, for example.
210 The string you set here will be appe 104 The string you set here will be appended after the contents of
211 any files with a filename matching l 105 any files with a filename matching localversion* in your
212 object and source tree, in that orde 106 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 107 be a maximum of 64 characters.
214 108
215 config LOCALVERSION_AUTO 109 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 110 bool "Automatically append version information to the version string"
217 default y 111 default y
218 depends on !COMPILE_TEST 112 depends on !COMPILE_TEST
219 help 113 help
220 This will try to automatically deter 114 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 115 release tree by looking for git tags that belong to the current
222 top of tree revision. 116 top of tree revision.
223 117
224 A string of the format -gxxxxxxxx wi 118 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 119 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 120 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 121 set in CONFIG_LOCALVERSION.
228 122
229 (The actual string used here is the !! 123 (The actual string used here is the first eight characters produced
230 by running the command: 124 by running the command:
231 125
232 $ git rev-parse --verify HEAD 126 $ git rev-parse --verify HEAD
233 127
234 which is done within the script "scr 128 which is done within the script "scripts/setlocalversion".)
235 129
236 config BUILD_SALT 130 config BUILD_SALT
237 string "Build ID Salt" !! 131 string "Build ID Salt"
238 default "" !! 132 default ""
239 help !! 133 help
240 The build ID is used to link binarie !! 134 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th !! 135 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi !! 136 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's !! 137 build is unique between builds. It's safe to leave the default.
244 138
245 config HAVE_KERNEL_GZIP 139 config HAVE_KERNEL_GZIP
246 bool 140 bool
247 141
248 config HAVE_KERNEL_BZIP2 142 config HAVE_KERNEL_BZIP2
249 bool 143 bool
250 144
251 config HAVE_KERNEL_LZMA 145 config HAVE_KERNEL_LZMA
252 bool 146 bool
253 147
254 config HAVE_KERNEL_XZ 148 config HAVE_KERNEL_XZ
255 bool 149 bool
256 150
257 config HAVE_KERNEL_LZO 151 config HAVE_KERNEL_LZO
258 bool 152 bool
259 153
260 config HAVE_KERNEL_LZ4 154 config HAVE_KERNEL_LZ4
261 bool 155 bool
262 156
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED 157 config HAVE_KERNEL_UNCOMPRESSED
267 bool 158 bool
268 159
269 choice 160 choice
270 prompt "Kernel compression mode" 161 prompt "Kernel compression mode"
271 default KERNEL_GZIP 162 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 163 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
273 help 164 help
274 The linux kernel is a kind of self-e 165 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 166 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 167 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 168 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 169 Decompression speed is relevant at each boot.
279 170
280 If you have any problems with bzip2 171 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 172 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 173 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 174 supplied by Christian Ludwig)
284 175
285 High compression options are mostly 176 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 177 are low on disk space (embedded systems), but for whom ram
287 size matters less. 178 size matters less.
288 179
289 If in doubt, select 'gzip' 180 If in doubt, select 'gzip'
290 181
291 config KERNEL_GZIP 182 config KERNEL_GZIP
292 bool "Gzip" 183 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 184 depends on HAVE_KERNEL_GZIP
294 help 185 help
295 The old and tried gzip compression. 186 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 187 between compression ratio and decompression speed.
297 188
298 config KERNEL_BZIP2 189 config KERNEL_BZIP2
299 bool "Bzip2" 190 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 191 depends on HAVE_KERNEL_BZIP2
301 help 192 help
302 Its compression ratio and speed is i 193 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 194 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 195 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 196 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 197 will need at least 8MB RAM or more for booting.
307 198
308 config KERNEL_LZMA 199 config KERNEL_LZMA
309 bool "LZMA" 200 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 201 depends on HAVE_KERNEL_LZMA
311 help 202 help
312 This compression algorithm's ratio i 203 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 204 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 205 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 206
316 config KERNEL_XZ 207 config KERNEL_XZ
317 bool "XZ" 208 bool "XZ"
318 depends on HAVE_KERNEL_XZ 209 depends on HAVE_KERNEL_XZ
319 help 210 help
320 XZ uses the LZMA2 algorithm and inst 211 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 212 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 213 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 214 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 215 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 216 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 217
328 The speed is about the same as with 218 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 219 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 220 and LZO. Compression is slow.
331 221
332 config KERNEL_LZO 222 config KERNEL_LZO
333 bool "LZO" 223 bool "LZO"
334 depends on HAVE_KERNEL_LZO 224 depends on HAVE_KERNEL_LZO
335 help 225 help
336 Its compression ratio is the poorest 226 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 227 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 228 (both compression and decompression) is the fastest.
339 229
340 config KERNEL_LZ4 230 config KERNEL_LZ4
341 bool "LZ4" 231 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 232 depends on HAVE_KERNEL_LZ4
343 help 233 help
344 LZ4 is an LZ77-type compressor with 234 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 235 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 236 <https://code.google.com/p/lz4/>.
347 237
348 Its compression ratio is worse than 238 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 239 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 240 faster than LZO.
351 241
352 config KERNEL_ZSTD <<
353 bool "ZSTD" <<
354 depends on HAVE_KERNEL_ZSTD <<
355 help <<
356 ZSTD is a compression algorithm targ <<
357 with fast decompression speed. It wi <<
358 decompress around the same speed as <<
359 will need at least 192 KB RAM or mor <<
360 line tool is required for compressio <<
361 <<
362 config KERNEL_UNCOMPRESSED 242 config KERNEL_UNCOMPRESSED
363 bool "None" 243 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 244 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 245 help
366 Produce uncompressed kernel image. T 246 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 247 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 248 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 249 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 250 and jump right at uncompressed kernel image.
371 251
372 endchoice 252 endchoice
373 253
374 config DEFAULT_INIT <<
375 string "Default init path" <<
376 default "" <<
377 help <<
378 This option determines the default i <<
379 option is passed on the kernel comma <<
380 not present, we will still then move <<
381 locations (e.g. /sbin/init, etc). If <<
382 the fallback list when init= is not <<
383 <<
384 config DEFAULT_HOSTNAME 254 config DEFAULT_HOSTNAME
385 string "Default hostname" 255 string "Default hostname"
386 default "(none)" 256 default "(none)"
387 help 257 help
388 This option determines the default s 258 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 259 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 260 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 261 system more usable with less configuration.
392 262
>> 263 #
>> 264 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 265 # add proper SWAP support to them, in which case this can be remove.
>> 266 #
>> 267 config ARCH_NO_SWAP
>> 268 bool
>> 269
>> 270 config SWAP
>> 271 bool "Support for paging of anonymous memory (swap)"
>> 272 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 273 default y
>> 274 help
>> 275 This option allows you to choose whether you want to have support
>> 276 for so called swap devices or swap files in your kernel that are
>> 277 used to provide more virtual memory than the actual RAM present
>> 278 in your computer. If unsure say Y.
>> 279
393 config SYSVIPC 280 config SYSVIPC
394 bool "System V IPC" 281 bool "System V IPC"
395 help !! 282 ---help---
396 Inter Process Communication is a sui 283 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 284 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 285 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 286 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 287 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 288 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 289 you'll need to say Y here.
403 290
404 You can find documentation about IPC 291 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 292 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 293 <http://www.tldp.org/guides.html>.
407 294
408 config SYSVIPC_SYSCTL 295 config SYSVIPC_SYSCTL
409 bool 296 bool
410 depends on SYSVIPC 297 depends on SYSVIPC
411 depends on SYSCTL 298 depends on SYSCTL
412 default y 299 default y
413 300
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 301 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 302 bool "POSIX Message Queues"
420 depends on NET 303 depends on NET
421 help !! 304 ---help---
422 POSIX variant of message queues is a 305 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 306 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 307 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 308 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 309 queues (functions mq_*) say Y here.
427 310
428 POSIX message queues are visible as 311 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 312 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 313 operations on message queues.
431 314
432 If unsure, say Y. 315 If unsure, say Y.
433 316
434 config POSIX_MQUEUE_SYSCTL 317 config POSIX_MQUEUE_SYSCTL
435 bool 318 bool
436 depends on POSIX_MQUEUE 319 depends on POSIX_MQUEUE
437 depends on SYSCTL 320 depends on SYSCTL
438 default y 321 default y
439 322
440 config WATCH_QUEUE <<
441 bool "General notification queue" <<
442 default n <<
443 help <<
444 <<
445 This is a general notification queue <<
446 userspace by splicing them into pipe <<
447 with watches for key/keyring change <<
448 notifications. <<
449 <<
450 See Documentation/core-api/watch_que <<
451 <<
452 config CROSS_MEMORY_ATTACH 323 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 324 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 325 depends on MMU
455 default y 326 default y
456 help 327 help
457 Enabling this option adds the system 328 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 329 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 330 to directly read from or write to another process' address space.
460 See the man page for more details. 331 See the man page for more details.
461 332
462 config USELIB 333 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 334 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 335 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 336 help
466 This option enables the uselib sysca 337 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 338 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 339 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 340 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 341 running glibc can safely disable this.
471 342
472 config AUDIT 343 config AUDIT
473 bool "Auditing support" 344 bool "Auditing support"
474 depends on NET 345 depends on NET
475 help 346 help
476 Enable auditing infrastructure that 347 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 348 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 349 logging of avc messages output). System call auditing is included
479 on architectures which support it. 350 on architectures which support it.
480 351
481 config HAVE_ARCH_AUDITSYSCALL 352 config HAVE_ARCH_AUDITSYSCALL
482 bool 353 bool
483 354
484 config AUDITSYSCALL 355 config AUDITSYSCALL
485 def_bool y 356 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 357 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 358 select FSNOTIFY
488 359
489 source "kernel/irq/Kconfig" 360 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 361 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 362 source "kernel/Kconfig.preempt"
493 363
494 menu "CPU/Task time and stats accounting" 364 menu "CPU/Task time and stats accounting"
495 365
496 config VIRT_CPU_ACCOUNTING 366 config VIRT_CPU_ACCOUNTING
497 bool 367 bool
498 368
499 choice 369 choice
500 prompt "Cputime accounting" 370 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 371 default TICK_CPU_ACCOUNTING if !PPC64
>> 372 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 373
503 # Kind of a stub config for the pure tick base 374 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 375 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 376 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 377 depends on !S390 && !NO_HZ_FULL
507 help 378 help
508 This is the basic tick based cputime 379 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 380 statistics about user, system and idle time spent on per jiffies
510 granularity. 381 granularity.
511 382
512 If unsure, say Y. 383 If unsure, say Y.
513 384
514 config VIRT_CPU_ACCOUNTING_NATIVE 385 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 386 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 387 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 388 select VIRT_CPU_ACCOUNTING
518 help 389 help
519 Select this option to enable more ac 390 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 391 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 392 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 393 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 394 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 395 this also enables accounting of stolen time on logically-partitioned
525 systems. 396 systems.
526 397
527 config VIRT_CPU_ACCOUNTING_GEN 398 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 399 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 400 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 401 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 402 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 403 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 404 select CONTEXT_TRACKING
534 help 405 help
535 Select this option to enable task an 406 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 407 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 408 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 409 The accounting is thus performed at the expense of some significant
539 overhead. 410 overhead.
540 411
541 For now this is only useful if you a 412 For now this is only useful if you are working on the full
542 dynticks subsystem development. 413 dynticks subsystem development.
543 414
544 If unsure, say N. 415 If unsure, say N.
545 416
546 endchoice 417 endchoice
547 418
548 config IRQ_TIME_ACCOUNTING 419 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 420 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 421 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 422 help
552 Select this option to enable fine gr 423 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 424 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 425 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 426 small performance impact.
556 427
557 If in doubt, say N here. 428 If in doubt, say N here.
558 429
559 config HAVE_SCHED_AVG_IRQ 430 config HAVE_SCHED_AVG_IRQ
560 def_bool y 431 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 432 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 433 depends on SMP
563 434
564 config SCHED_HW_PRESSURE <<
565 bool <<
566 default y if ARM && ARM_CPU_TOPOLOGY <<
567 default y if ARM64 <<
568 depends on SMP <<
569 depends on CPU_FREQ_THERMAL <<
570 help <<
571 Select this option to enable HW pres <<
572 scheduler. HW pressure is the value <<
573 that reflects the reduction in CPU c <<
574 HW throttling. HW throttling occurs <<
575 a CPU is capped due to high operatin <<
576 <<
577 If selected, the scheduler will be a <<
578 i.e. put less load on throttled CPUs <<
579 <<
580 This requires the architecture to im <<
581 arch_update_hw_pressure() and arch_s <<
582 <<
583 config BSD_PROCESS_ACCT 435 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 436 bool "BSD Process Accounting"
585 depends on MULTIUSER 437 depends on MULTIUSER
586 help 438 help
587 If you say Y here, a user level prog 439 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 440 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 441 information to a file: whenever a process exits, information about
590 that process will be appended to the 442 that process will be appended to the file by the kernel. The
591 information includes things such as 443 information includes things such as creation time, owning user,
592 command name, memory usage, controll 444 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 445 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 446 up to the user level program to do useful things with this
595 information. This is generally a go 447 information. This is generally a good idea, so say Y.
596 448
597 config BSD_PROCESS_ACCT_V3 449 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 450 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 451 depends on BSD_PROCESS_ACCT
600 default n 452 default n
601 help 453 help
602 If you say Y here, the process accou 454 If you say Y here, the process accounting information is written
603 in a new file format that also logs 455 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 456 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 457 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 458 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 459 at <http://www.gnu.org/software/acct/>.
608 460
609 config TASKSTATS 461 config TASKSTATS
610 bool "Export task/process statistics t 462 bool "Export task/process statistics through netlink"
611 depends on NET 463 depends on NET
612 depends on MULTIUSER 464 depends on MULTIUSER
613 default n 465 default n
614 help 466 help
615 Export selected statistics for tasks 467 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 468 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 469 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 470 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 471 space on task exit.
620 472
621 Say N if unsure. 473 Say N if unsure.
622 474
623 config TASK_DELAY_ACCT 475 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 476 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 477 depends on TASKSTATS
626 select SCHED_INFO 478 select SCHED_INFO
627 help 479 help
628 Collect information on time spent by 480 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 481 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 482 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 483 relative to other tasks for cpu, io, rss limits etc.
632 484
633 Say N if unsure. 485 Say N if unsure.
634 486
635 config TASK_XACCT 487 config TASK_XACCT
636 bool "Enable extended accounting over 488 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 489 depends on TASKSTATS
638 help 490 help
639 Collect extended task accounting dat 491 Collect extended task accounting data and send the data
640 to userland for processing over the 492 to userland for processing over the taskstats interface.
641 493
642 Say N if unsure. 494 Say N if unsure.
643 495
644 config TASK_IO_ACCOUNTING 496 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 497 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 498 depends on TASK_XACCT
647 help 499 help
648 Collect information on the number of 500 Collect information on the number of bytes of storage I/O which this
649 task has caused. 501 task has caused.
650 502
651 Say N if unsure. 503 Say N if unsure.
652 504
653 config PSI 505 config PSI
654 bool "Pressure stall information track 506 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 507 help
657 Collect metrics that indicate how ov 508 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 509 and IO capacity are in the system.
659 510
660 If you say Y here, the kernel will c 511 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 512 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 513 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 514 delayed due to contention of the respective resource.
664 515
665 In kernels with cgroup support, cgro 516 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 517 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 518 which aggregate pressure stalls for the grouped tasks only.
668 519
669 For more details see Documentation/a !! 520 For more details see Documentation/accounting/psi.txt.
670 521
671 Say N if unsure. 522 Say N if unsure.
672 523
673 config PSI_DEFAULT_DISABLED 524 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 525 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 526 default n
676 depends on PSI 527 depends on PSI
677 help 528 help
678 If set, pressure stall information t 529 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 530 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 531 kernel commandline during boot.
681 532
682 This feature adds some code to the t 533 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 534 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 535 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 536 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 537 scheduler stress tests, such as hackbench.
687 538
688 If you are paranoid and not sure wha 539 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 540 used for, say Y.
690 541
691 Say N if unsure. 542 Say N if unsure.
692 543
693 endmenu # "CPU/Task time and stats accounting" 544 endmenu # "CPU/Task time and stats accounting"
694 545
695 config CPU_ISOLATION 546 config CPU_ISOLATION
696 bool "CPU isolation" 547 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 548 depends on SMP || COMPILE_TEST
698 default y 549 default y
699 help 550 help
700 Make sure that CPUs running critical 551 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 552 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 553 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 554 the "isolcpus=" boot parameter.
704 555
705 Say Y if unsure. 556 Say Y if unsure.
706 557
707 source "kernel/rcu/Kconfig" 558 source "kernel/rcu/Kconfig"
708 559
>> 560 config BUILD_BIN2C
>> 561 bool
>> 562 default n
>> 563
709 config IKCONFIG 564 config IKCONFIG
710 tristate "Kernel .config support" 565 tristate "Kernel .config support"
711 help !! 566 ---help---
712 This option enables the complete Lin 567 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 568 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 569 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 570 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 571 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 572 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 573 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 574 /proc/config.gz if enabled (below).
720 575
721 config IKCONFIG_PROC 576 config IKCONFIG_PROC
722 bool "Enable access to .config through 577 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 578 depends on IKCONFIG && PROC_FS
724 help !! 579 ---help---
725 This option enables access to the ke 580 This option enables access to the kernel configuration file
726 through /proc/config.gz. 581 through /proc/config.gz.
727 582
728 config IKHEADERS 583 config IKHEADERS
729 tristate "Enable kernel headers throug 584 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 585 depends on SYSFS
731 help 586 help
732 This option enables access to the in 587 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 588 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 589 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 590 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 591
737 config LOG_BUF_SHIFT 592 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 593 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 594 range 12 25
740 default 17 595 default 17
741 depends on PRINTK 596 depends on PRINTK
742 help 597 help
743 Select the minimal kernel log buffer 598 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 599 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 600 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 601 by "log_buf_len" boot parameter.
747 602
748 Examples: 603 Examples:
749 17 => 128 KB 604 17 => 128 KB
750 16 => 64 KB 605 16 => 64 KB
751 15 => 32 KB 606 15 => 32 KB
752 14 => 16 KB 607 14 => 16 KB
753 13 => 8 KB 608 13 => 8 KB
754 12 => 4 KB 609 12 => 4 KB
755 610
756 config LOG_CPU_MAX_BUF_SHIFT 611 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 612 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 613 depends on SMP
759 range 0 21 614 range 0 21
>> 615 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 616 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 617 depends on PRINTK
763 help 618 help
764 This option allows to increase the d 619 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 620 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 621 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 622 lines however it might be much more when problems are reported,
768 e.g. backtraces. 623 e.g. backtraces.
769 624
770 The increased size means that a new 625 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 626 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 627 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 628 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 629 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 630 so that more than 64 CPUs are needed to trigger the allocation.
776 631
777 Also this option is ignored when "lo 632 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 633 used as it forces an exact (power of two) size of the ring buffer.
779 634
780 The number of possible CPUs is used 635 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 636 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 637 scenario while allowing a simple algorithm to be used from bootup.
783 638
784 Examples shift values and their mean 639 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 640 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 641 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 642 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 643 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 644 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 645 12 => 4 KB for each CPU
791 646
792 config PRINTK_INDEX !! 647 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 648 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 649 range 10 21
795 help !! 650 default 13
796 Add support for indexing of all prin !! 651 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 652 help
798 !! 653 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 654 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 655 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 656 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 657 The value defines the size as a power of 2.
>> 658
>> 659 Those messages are rare and limited. The largest one is when
>> 660 a backtrace is printed. It usually fits into 4KB. Select
>> 661 8KB if you want to be on the safe side.
803 662
804 There is no additional runtime cost !! 663 Examples:
>> 664 17 => 128 KB for each CPU
>> 665 16 => 64 KB for each CPU
>> 666 15 => 32 KB for each CPU
>> 667 14 => 16 KB for each CPU
>> 668 13 => 8 KB for each CPU
>> 669 12 => 4 KB for each CPU
805 670
806 # 671 #
807 # Architectures with an unreliable sched_clock 672 # Architectures with an unreliable sched_clock() should select this:
808 # 673 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 674 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 675 bool
811 676
812 config GENERIC_SCHED_CLOCK 677 config GENERIC_SCHED_CLOCK
813 bool 678 bool
814 679
815 menu "Scheduler features" <<
816 <<
817 config UCLAMP_TASK <<
818 bool "Enable utilization clamping for <<
819 depends on CPU_FREQ_GOV_SCHEDUTIL <<
820 help <<
821 This feature enables the scheduler t <<
822 of each CPU based on RUNNABLE tasks <<
823 <<
824 With this option, the user can speci <<
825 utilization allowed for RUNNABLE tas <<
826 the maximum frequency a task should <<
827 defines the minimum frequency it sho <<
828 <<
829 Both min and max utilization clamp v <<
830 aiming at improving its frequency se <<
831 enforce or grant any specific bandwi <<
832 <<
833 If in doubt, say N. <<
834 <<
835 config UCLAMP_BUCKETS_COUNT <<
836 int "Number of supported utilization c <<
837 range 5 20 <<
838 default 5 <<
839 depends on UCLAMP_TASK <<
840 help <<
841 Defines the number of clamp buckets <<
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ <<
843 number of clamp buckets the finer th <<
844 the precision of clamping aggregatio <<
845 <<
846 For example, with the minimum config <<
847 clamp buckets tracking 20% utilizati <<
848 be refcounted in the [20..39]% bucke <<
849 effective value to 25%. <<
850 If a second 30% boosted task should <<
851 that task will be refcounted in the <<
852 it will boost the bucket clamp effec <<
853 The clamp effective value of a bucke <<
854 (20% in the example above) when ther <<
855 that bucket. <<
856 <<
857 An additional boost/capping margin c <<
858 example above the 25% task will be b <<
859 CPU. If that should be considered no <<
860 it's always possible to reduce the m <<
861 clamp buckets to trade off used memo <<
862 precision. <<
863 <<
864 If in doubt, use the default value. <<
865 <<
866 endmenu <<
867 <<
868 # 680 #
869 # For architectures that want to enable the su 681 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 682 # balancing logic:
871 # 683 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 684 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 685 bool
874 686
875 # 687 #
876 # For architectures that prefer to flush all T 688 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 689 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 690 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 691 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 692 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 693 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 694 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 695 bool
884 696
885 config CC_HAS_INT128 <<
886 def_bool !$(cc-option,$(m64-flag) -D__ <<
887 <<
888 config CC_IMPLICIT_FALLTHROUGH <<
889 string <<
890 default "-Wimplicit-fallthrough=5" if <<
891 default "-Wimplicit-fallthrough" if CC <<
892 <<
893 # Currently, disable gcc-10+ array-bounds glob <<
894 # It's still broken in gcc-13, so no upper bou <<
895 config GCC10_NO_ARRAY_BOUNDS <<
896 def_bool y <<
897 <<
898 config CC_NO_ARRAY_BOUNDS <<
899 bool <<
900 default y if CC_IS_GCC && GCC_VERSION <<
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 <<
914 # 697 #
915 # For architectures that know their GCC __int1 698 # For architectures that know their GCC __int128 support is sound
916 # 699 #
917 config ARCH_SUPPORTS_INT128 700 config ARCH_SUPPORTS_INT128
918 bool 701 bool
919 702
920 # For architectures that (ab)use NUMA to repre 703 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 704 # all cpu-local but of different latencies, such as SuperH.
922 # 705 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 706 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 707 bool
925 708
926 config NUMA_BALANCING 709 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 710 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 711 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 712 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 713 depends on SMP && NUMA && MIGRATION
931 help 714 help
932 This option adds support for automat 715 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 716 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 717 it has references to the node the task is running on.
935 718
936 This system will be inactive on UMA 719 This system will be inactive on UMA systems.
937 720
938 config NUMA_BALANCING_DEFAULT_ENABLED 721 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 722 bool "Automatically enable NUMA aware memory/task placement"
940 default y 723 default y
941 depends on NUMA_BALANCING 724 depends on NUMA_BALANCING
942 help 725 help
943 If set, automatic NUMA balancing wil 726 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 727 machine.
945 728
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 729 menuconfig CGROUPS
950 bool "Control Group support" 730 bool "Control Group support"
951 select KERNFS 731 select KERNFS
952 help 732 help
953 This option adds support for groupin 733 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 734 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 735 controls or device isolation.
956 See 736 See
957 - Documentation/scheduler/sche !! 737 - Documentation/scheduler/sched-design-CFS.txt (CFS)
958 - Documentation/admin-guide/cg !! 738 - Documentation/cgroup-v1/ (features for grouping, isolation
959 and 739 and resource control)
960 740
961 Say N if unsure. 741 Say N if unsure.
962 742
963 if CGROUPS 743 if CGROUPS
964 744
965 config PAGE_COUNTER 745 config PAGE_COUNTER
966 bool !! 746 bool
967 <<
968 config CGROUP_FAVOR_DYNMODS <<
969 bool "Favor dynamic modification laten <<
970 help <<
971 This option enables the "favordynmod <<
972 which reduces the latencies of dynam <<
973 as task migrations and controller on <<
974 hot path operations such as forks an <<
975 <<
976 Say N if unsure. <<
977 747
978 config MEMCG 748 config MEMCG
979 bool "Memory controller" 749 bool "Memory controller"
980 select PAGE_COUNTER 750 select PAGE_COUNTER
981 select EVENTFD 751 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 752 help
984 Provides control over the memory foo 753 Provides control over the memory footprint of tasks in a cgroup.
985 754
986 config MEMCG_V1 !! 755 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 756 bool "Swap controller"
988 depends on MEMCG !! 757 depends on MEMCG && SWAP
989 default n <<
990 help 758 help
991 Legacy cgroup v1 memory controller w !! 759 Provides control over the swap space consumed by tasks in a cgroup.
992 cgroup v2 implementation. The v1 is <<
993 which haven't migrated to the new cg <<
994 do not have any such application the <<
995 this option disabled. <<
996 <<
997 Please note that feature set of the <<
998 going to shrink due to deprecation p <<
999 controller are highly discouraged. <<
1000 760
1001 Say N if unsure. !! 761 config MEMCG_SWAP_ENABLED
>> 762 bool "Swap controller enabled by default"
>> 763 depends on MEMCG_SWAP
>> 764 default y
>> 765 help
>> 766 Memory Resource Controller Swap Extension comes with its price in
>> 767 a bigger memory consumption. General purpose distribution kernels
>> 768 which want to enable the feature but keep it disabled by default
>> 769 and let the user enable it by swapaccount=1 boot command line
>> 770 parameter should have this option unselected.
>> 771 For those who want to have the feature enabled by default should
>> 772 select this option (if, for some reason, they need to disable it
>> 773 then swapaccount=0 does the trick).
>> 774
>> 775 config MEMCG_KMEM
>> 776 bool
>> 777 depends on MEMCG && !SLOB
>> 778 default y
1002 779
1003 config BLK_CGROUP 780 config BLK_CGROUP
1004 bool "IO controller" 781 bool "IO controller"
1005 depends on BLOCK 782 depends on BLOCK
1006 default n 783 default n
1007 help !! 784 ---help---
1008 Generic block IO controller cgroup in 785 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 786 cgroup interface which should be used by various IO controlling
1010 policies. 787 policies.
1011 788
1012 Currently, CFQ IO scheduler uses it t 789 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 790 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 791 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 792 block layer to implement upper limit in IO rates on a device.
1016 793
1017 This option only enables generic Bloc 794 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 795 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 796 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 797 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 798 CONFIG_BLK_DEV_THROTTLING=y.
1022 799
1023 See Documentation/admin-guide/cgroup- !! 800 See Documentation/cgroup-v1/blkio-controller.txt for more information.
>> 801
>> 802 config DEBUG_BLK_CGROUP
>> 803 bool "IO controller debugging"
>> 804 depends on BLK_CGROUP
>> 805 default n
>> 806 ---help---
>> 807 Enable some debugging help. Currently it exports additional stat
>> 808 files in a cgroup which can be useful for debugging.
1024 809
1025 config CGROUP_WRITEBACK 810 config CGROUP_WRITEBACK
1026 bool 811 bool
1027 depends on MEMCG && BLK_CGROUP 812 depends on MEMCG && BLK_CGROUP
1028 default y 813 default y
1029 814
1030 menuconfig CGROUP_SCHED 815 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 816 bool "CPU controller"
1032 default n 817 default n
1033 help 818 help
1034 This feature lets CPU scheduler rec 819 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 820 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 821 tasks.
1037 822
1038 if CGROUP_SCHED 823 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 824 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 825 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 826 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 827 default CGROUP_SCHED
1047 828
1048 config CFS_BANDWIDTH 829 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 830 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 831 depends on FAIR_GROUP_SCHED
1051 default n 832 default n
1052 help 833 help
1053 This option allows users to define 834 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 835 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 836 set are considered to be unconstrained and will run with no
1056 restriction. 837 restriction.
1057 See Documentation/scheduler/sched-b !! 838 See Documentation/scheduler/sched-bwc.txt for more information.
1058 839
1059 config RT_GROUP_SCHED 840 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 841 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 842 depends on CGROUP_SCHED
1062 default n 843 default n
1063 help 844 help
1064 This feature lets you explicitly al 845 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 846 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 847 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 848 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r !! 849 See Documentation/scheduler/sched-rt-group.txt for more information.
1069 <<
1070 config EXT_GROUP_SCHED <<
1071 bool <<
1072 depends on SCHED_CLASS_EXT && CGROUP_ <<
1073 select GROUP_SCHED_WEIGHT <<
1074 default y <<
1075 850
1076 endif #CGROUP_SCHED 851 endif #CGROUP_SCHED
1077 852
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP <<
1083 bool "Utilization clamping per group <<
1084 depends on CGROUP_SCHED <<
1085 depends on UCLAMP_TASK <<
1086 default n <<
1087 help <<
1088 This feature enables the scheduler <<
1089 of each CPU based on RUNNABLE tasks <<
1090 <<
1091 When this option is enabled, the us <<
1092 CPU bandwidth which is allowed for <<
1093 The max bandwidth allows to clamp t <<
1094 can use, while the min bandwidth al <<
1095 frequency a task will always use. <<
1096 <<
1097 When task group based utilization c <<
1098 specified task-specific clamp value <<
1099 specified clamp value. Both minimum <<
1100 be bigger than the corresponding cl <<
1101 <<
1102 If in doubt, say N. <<
1103 <<
1104 config CGROUP_PIDS 853 config CGROUP_PIDS
1105 bool "PIDs controller" 854 bool "PIDs controller"
1106 help 855 help
1107 Provides enforcement of process num 856 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 857 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 858 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 859 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 860 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 861 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 862 PIDs controller is designed to stop this from happening.
1114 863
1115 It should be noted that organisatio 864 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 865 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 866 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 867 attach to a cgroup.
1119 868
1120 config CGROUP_RDMA 869 config CGROUP_RDMA
1121 bool "RDMA controller" 870 bool "RDMA controller"
1122 help 871 help
1123 Provides enforcement of RDMA resour 872 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 873 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 874 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 875 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 876 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 877 hierarchy is allowed even if can cross the hierarchy's limit.
1129 878
1130 config CGROUP_FREEZER 879 config CGROUP_FREEZER
1131 bool "Freezer controller" 880 bool "Freezer controller"
1132 help 881 help
1133 Provides a way to freeze and unfree 882 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 883 cgroup.
1135 884
1136 This option affects the ORIGINAL cg 885 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 886 controller includes important in-kernel memory consumers per default.
1138 887
1139 If you're using cgroup2, say N. 888 If you're using cgroup2, say N.
1140 889
1141 config CGROUP_HUGETLB 890 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 891 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 892 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 893 select PAGE_COUNTER
1145 default n 894 default n
1146 help 895 help
1147 Provides a cgroup controller for Hu 896 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 897 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 898 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 899 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 900 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 901 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 902 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 903 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 904 that we cannot use the controller with huge page less than 3 pages.
1156 905
1157 config CPUSETS 906 config CPUSETS
1158 bool "Cpuset controller" 907 bool "Cpuset controller"
1159 depends on SMP 908 depends on SMP
1160 help 909 help
1161 This option will let you create and 910 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 911 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 912 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 913 This is primarily useful on large SMP or NUMA systems.
1165 914
1166 Say N if unsure. 915 Say N if unsure.
1167 916
1168 config CPUSETS_V1 <<
1169 bool "Legacy cgroup v1 cpusets contro <<
1170 depends on CPUSETS <<
1171 default n <<
1172 help <<
1173 Legacy cgroup v1 cpusets controller <<
1174 cgroup v2 implementation. The v1 is <<
1175 which haven't migrated to the new c <<
1176 do not have any such application th <<
1177 this option disabled. <<
1178 <<
1179 Say N if unsure. <<
1180 <<
1181 config PROC_PID_CPUSET 917 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 918 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 919 depends on CPUSETS
1184 default y 920 default y
1185 921
1186 config CGROUP_DEVICE 922 config CGROUP_DEVICE
1187 bool "Device controller" 923 bool "Device controller"
1188 help 924 help
1189 Provides a cgroup controller implem 925 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 926 devices which a process in the cgroup can mknod or open.
1191 927
1192 config CGROUP_CPUACCT 928 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 929 bool "Simple CPU accounting controller"
1194 help 930 help
1195 Provides a simple controller for mo 931 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 932 total CPU consumed by the tasks in a cgroup.
1197 933
1198 config CGROUP_PERF 934 config CGROUP_PERF
1199 bool "Perf controller" 935 bool "Perf controller"
1200 depends on PERF_EVENTS 936 depends on PERF_EVENTS
1201 help 937 help
1202 This option extends the perf per-cp 938 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 939 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 940 designated cpu.
1205 so that it can monitor performance <<
1206 941
1207 Say N if unsure. 942 Say N if unsure.
1208 943
1209 config CGROUP_BPF 944 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 945 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 946 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 947 select SOCK_CGROUP_DATA
1213 help 948 help
1214 Allow attaching eBPF programs to a 949 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 950 syscall command BPF_PROG_ATTACH.
1216 951
1217 In which context these programs are 952 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 953 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 954 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 955 inet sockets.
1221 956
1222 config CGROUP_MISC <<
1223 bool "Misc resource controller" <<
1224 default n <<
1225 help <<
1226 Provides a controller for miscellan <<
1227 <<
1228 Miscellaneous scalar resources are <<
1229 which cannot be abstracted like the <<
1230 tracks and limits the miscellaneous <<
1231 attached to a cgroup hierarchy. <<
1232 <<
1233 For more information, please check <<
1234 /Documentation/admin-guide/cgroup-v <<
1235 <<
1236 config CGROUP_DEBUG 957 config CGROUP_DEBUG
1237 bool "Debug controller" 958 bool "Debug controller"
1238 default n 959 default n
1239 depends on DEBUG_KERNEL 960 depends on DEBUG_KERNEL
1240 help 961 help
1241 This option enables a simple contro 962 This option enables a simple controller that exports
1242 debugging information about the cgr 963 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 964 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 965 interfaces are not stable.
1245 966
1246 Say N. 967 Say N.
1247 968
1248 config SOCK_CGROUP_DATA 969 config SOCK_CGROUP_DATA
1249 bool 970 bool
1250 default n 971 default n
1251 972
1252 endif # CGROUPS 973 endif # CGROUPS
1253 974
1254 menuconfig NAMESPACES 975 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 976 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 977 depends on MULTIUSER
1257 default !EXPERT 978 default !EXPERT
1258 help 979 help
1259 Provides the way to make tasks work 980 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 981 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 982 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 983 different namespaces.
1263 984
1264 if NAMESPACES 985 if NAMESPACES
1265 986
1266 config UTS_NS 987 config UTS_NS
1267 bool "UTS namespace" 988 bool "UTS namespace"
1268 default y 989 default y
1269 help 990 help
1270 In this namespace tasks see differe 991 In this namespace tasks see different info provided with the
1271 uname() system call 992 uname() system call
1272 993
1273 config TIME_NS <<
1274 bool "TIME namespace" <<
1275 depends on GENERIC_VDSO_TIME_NS <<
1276 default y <<
1277 help <<
1278 In this namespace boottime and mono <<
1279 The time will keep going with the s <<
1280 <<
1281 config IPC_NS 994 config IPC_NS
1282 bool "IPC namespace" 995 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 996 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 997 default y
1285 help 998 help
1286 In this namespace tasks work with I 999 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1000 different IPC objects in different namespaces.
1288 1001
1289 config USER_NS 1002 config USER_NS
1290 bool "User namespace" 1003 bool "User namespace"
1291 default n 1004 default n
1292 help 1005 help
1293 This allows containers, i.e. vserve 1006 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1007 to provide different user info for different servers.
1295 1008
1296 When user namespaces are enabled in 1009 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1010 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1011 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1012 of memory a memory unprivileged users can use.
1300 1013
1301 If unsure, say N. 1014 If unsure, say N.
1302 1015
1303 config PID_NS 1016 config PID_NS
1304 bool "PID Namespaces" 1017 bool "PID Namespaces"
1305 default y 1018 default y
1306 help 1019 help
1307 Support process id namespaces. Thi 1020 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1021 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1022 pid namespaces. This is a building block of containers.
1310 1023
1311 config NET_NS 1024 config NET_NS
1312 bool "Network namespace" 1025 bool "Network namespace"
1313 depends on NET 1026 depends on NET
1314 default y 1027 default y
1315 help 1028 help
1316 Allow user space to create what app 1029 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1030 of the network stack.
1318 1031
1319 endif # NAMESPACES 1032 endif # NAMESPACES
1320 1033
1321 config CHECKPOINT_RESTORE 1034 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1035 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1036 select PROC_CHILDREN
1325 select KCMP <<
1326 default n 1037 default n
1327 help 1038 help
1328 Enables additional kernel features 1039 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1040 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1041 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1042 entries.
1332 1043
1333 If unsure, say N here. 1044 If unsure, say N here.
1334 1045
1335 config SCHED_AUTOGROUP 1046 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1047 bool "Automatic process group scheduling"
1337 select CGROUPS 1048 select CGROUPS
1338 select CGROUP_SCHED 1049 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1050 select FAIR_GROUP_SCHED
1340 help 1051 help
1341 This option optimizes the scheduler 1052 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1053 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1054 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1055 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1056 upon task session.
1346 1057
>> 1058 config SYSFS_DEPRECATED
>> 1059 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1060 depends on SYSFS
>> 1061 default n
>> 1062 help
>> 1063 This option adds code that switches the layout of the "block" class
>> 1064 devices, to not show up in /sys/class/block/, but only in
>> 1065 /sys/block/.
>> 1066
>> 1067 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1068 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1069
>> 1070 This option allows new kernels to run on old distributions and tools,
>> 1071 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1072 major distributions and tools handle this just fine.
>> 1073
>> 1074 Recent distributions and userspace tools after 2009/2010 depend on
>> 1075 the existence of /sys/class/block/, and will not work with this
>> 1076 option enabled.
>> 1077
>> 1078 Only if you are using a new kernel on an old distribution, you might
>> 1079 need to say Y here.
>> 1080
>> 1081 config SYSFS_DEPRECATED_V2
>> 1082 bool "Enable deprecated sysfs features by default"
>> 1083 default n
>> 1084 depends on SYSFS
>> 1085 depends on SYSFS_DEPRECATED
>> 1086 help
>> 1087 Enable deprecated sysfs by default.
>> 1088
>> 1089 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1090 option.
>> 1091
>> 1092 Only if you are using a new kernel on an old distribution, you might
>> 1093 need to say Y here. Even then, odds are you would not need it
>> 1094 enabled, you can always pass the boot option if absolutely necessary.
>> 1095
1347 config RELAY 1096 config RELAY
1348 bool "Kernel->user space relay suppor 1097 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1098 select IRQ_WORK
1350 help 1099 help
1351 This option enables support for rel 1100 This option enables support for relay interface support in
1352 certain file systems (such as debug 1101 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1102 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1103 facilities to relay large amounts of data from kernel space to
1355 user space. 1104 user space.
1356 1105
1357 If unsure, say N. 1106 If unsure, say N.
1358 1107
1359 config BLK_DEV_INITRD 1108 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1109 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1110 help
1362 The initial RAM filesystem is a ram 1111 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1112 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1113 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1114 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1115 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1116
1368 If RAM disk support (BLK_DEV_RAM) i 1117 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1118 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1119 15 Kbytes (more on some other architectures) to the kernel size.
1371 1120
1372 If unsure say Y. 1121 If unsure say Y.
1373 1122
1374 if BLK_DEV_INITRD 1123 if BLK_DEV_INITRD
1375 1124
1376 source "usr/Kconfig" 1125 source "usr/Kconfig"
1377 1126
1378 endif 1127 endif
1379 1128
1380 config BOOT_CONFIG <<
1381 bool "Boot config support" <<
1382 select BLK_DEV_INITRD if !BOOT_CONFIG <<
1383 help <<
1384 Extra boot config allows system adm <<
1385 complemental extension of kernel cm <<
1386 The boot config file must be attach <<
1387 with checksum, size and magic word. <<
1388 See <file:Documentation/admin-guide <<
1389 <<
1390 If unsure, say Y. <<
1391 <<
1392 config BOOT_CONFIG_FORCE <<
1393 bool "Force unconditional bootconfig <<
1394 depends on BOOT_CONFIG <<
1395 default y if BOOT_CONFIG_EMBED <<
1396 help <<
1397 With this Kconfig option set, BOOT_ <<
1398 out even when the "bootconfig" kern <<
1399 In fact, with this Kconfig option s <<
1400 make the kernel ignore the BOOT_CON <<
1401 parameters. <<
1402 <<
1403 If unsure, say N. <<
1404 <<
1405 config BOOT_CONFIG_EMBED <<
1406 bool "Embed bootconfig file in the ke <<
1407 depends on BOOT_CONFIG <<
1408 help <<
1409 Embed a bootconfig file given by BO <<
1410 kernel. Usually, the bootconfig fil <<
1411 image. But if the system doesn't su <<
1412 help you by embedding a bootconfig <<
1413 <<
1414 If unsure, say N. <<
1415 <<
1416 config BOOT_CONFIG_EMBED_FILE <<
1417 string "Embedded bootconfig file path <<
1418 depends on BOOT_CONFIG_EMBED <<
1419 help <<
1420 Specify a bootconfig file which wil <<
1421 This bootconfig will be used if the <<
1422 bootconfig in the initrd. <<
1423 <<
1424 config INITRAMFS_PRESERVE_MTIME <<
1425 bool "Preserve cpio archive mtimes in <<
1426 default y <<
1427 help <<
1428 Each entry in an initramfs cpio arc <<
1429 enabled, extracted cpio items take <<
1430 setting deferred until after creati <<
1431 <<
1432 If unsure, say Y. <<
1433 <<
1434 choice 1129 choice
1435 prompt "Compiler optimization level" 1130 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1131 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1132
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1133 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" !! 1134 bool "Optimize for performance"
1440 help 1135 help
1441 This is the default optimization le 1136 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1137 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1138 helpful compile-time warnings.
1444 1139
1445 config CC_OPTIMIZE_FOR_SIZE 1140 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" !! 1141 bool "Optimize for size"
>> 1142 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
1447 help 1143 help
1448 Choosing this option will pass "-Os !! 1144 Enabling this option will pass "-Os" instead of "-O2" to
1449 in a smaller kernel. !! 1145 your compiler resulting in a smaller kernel.
>> 1146
>> 1147 If unsure, say N.
1450 1148
1451 endchoice 1149 endchoice
1452 1150
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1151 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1152 bool
1455 help 1153 help
1456 This requires that the arch annotat 1154 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1155 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1156 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1157 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1158 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1159 is used to distinguish them from label names / C identifiers.
1462 1160
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1161 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1162 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1163 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1164 depends on EXPERT
>> 1165 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1467 depends on $(cc-option,-ffunction-sec 1166 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1167 depends on $(ld-option,--gc-sections)
1469 help 1168 help
1470 Enable this if you want to do dead 1169 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1170 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1171 and linking with --gc-sections.
1473 1172
1474 This can reduce on disk and in-memo 1173 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1174 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1175 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1176 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1177 present. This option is not well tested yet, so use at your
1479 own risk. 1178 own risk.
1480 1179
1481 config LD_ORPHAN_WARN <<
1482 def_bool y <<
1483 depends on ARCH_WANT_LD_ORPHAN_WARN <<
1484 depends on $(ld-option,--orphan-handl <<
1485 depends on $(ld-option,--orphan-handl <<
1486 <<
1487 config LD_ORPHAN_WARN_LEVEL <<
1488 string <<
1489 depends on LD_ORPHAN_WARN <<
1490 default "error" if WERROR <<
1491 default "warn" <<
1492 <<
1493 config SYSCTL 1180 config SYSCTL
1494 bool 1181 bool
1495 1182
1496 config HAVE_UID16 1183 config HAVE_UID16
1497 bool 1184 bool
1498 1185
1499 config SYSCTL_EXCEPTION_TRACE 1186 config SYSCTL_EXCEPTION_TRACE
1500 bool 1187 bool
1501 help 1188 help
1502 Enable support for /proc/sys/debug/ 1189 Enable support for /proc/sys/debug/exception-trace.
1503 1190
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1191 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1192 bool
1506 help 1193 help
1507 Enable support for /proc/sys/kernel 1194 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1195 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1196 about unaligned access emulation going on under the hood.
1510 1197
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1198 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1199 bool
1513 help 1200 help
1514 Enable support for /proc/sys/kernel 1201 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1202 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1203 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1204 see arch/parisc/kernel/unaligned.c for reference
1518 1205
1519 config HAVE_PCSPKR_PLATFORM 1206 config HAVE_PCSPKR_PLATFORM
1520 bool 1207 bool
1521 1208
>> 1209 # interpreter that classic socket filters depend on
>> 1210 config BPF
>> 1211 bool
>> 1212
1522 menuconfig EXPERT 1213 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1214 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1215 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1216 select DEBUG_KERNEL
1526 help 1217 help
1527 This option allows certain base ker 1218 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is !! 1219 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " !! 1220 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh !! 1221 Only use this if you really know what you are doing.
1531 1222
1532 config UID16 1223 config UID16
1533 bool "Enable 16-bit UID system calls" 1224 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1225 depends on HAVE_UID16 && MULTIUSER
1535 default y 1226 default y
1536 help 1227 help
1537 This enables the legacy 16-bit UID 1228 This enables the legacy 16-bit UID syscall wrappers.
1538 1229
1539 config MULTIUSER 1230 config MULTIUSER
1540 bool "Multiple users, groups and capa 1231 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1232 default y
1542 help 1233 help
1543 This option enables support for non 1234 This option enables support for non-root users, groups and
1544 capabilities. 1235 capabilities.
1545 1236
1546 If you say N here, all processes wi 1237 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1238 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1239 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1240 setgid, and capset.
1550 1241
1551 If unsure, say Y here. 1242 If unsure, say Y here.
1552 1243
1553 config SGETMASK_SYSCALL 1244 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1245 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1246 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help !! 1247 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1248 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1249 no longer supported in libc but still enabled by default in some
1559 architectures. 1250 architectures.
1560 1251
1561 If unsure, leave the default option 1252 If unsure, leave the default option here.
1562 1253
1563 config SYSFS_SYSCALL 1254 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1255 bool "Sysfs syscall support" if EXPERT
1565 default y 1256 default y
1566 help !! 1257 ---help---
1567 sys_sysfs is an obsolete system cal 1258 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1259 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1260 compatibility with some systems.
1570 1261
1571 If unsure say Y here. 1262 If unsure say Y here.
1572 1263
>> 1264 config SYSCTL_SYSCALL
>> 1265 bool "Sysctl syscall support" if EXPERT
>> 1266 depends on PROC_SYSCTL
>> 1267 default n
>> 1268 select SYSCTL
>> 1269 ---help---
>> 1270 sys_sysctl uses binary paths that have been found challenging
>> 1271 to properly maintain and use. The interface in /proc/sys
>> 1272 using paths with ascii names is now the primary path to this
>> 1273 information.
>> 1274
>> 1275 Almost nothing using the binary sysctl interface so if you are
>> 1276 trying to save some space it is probably safe to disable this,
>> 1277 making your kernel marginally smaller.
>> 1278
>> 1279 If unsure say N here.
>> 1280
1573 config FHANDLE 1281 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1282 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1283 select EXPORTFS
1576 default y 1284 default y
1577 help 1285 help
1578 If you say Y here, a user level pro 1286 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1287 file names to handle and then later use the handle for
1580 different file system operations. T 1288 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1289 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1290 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1291 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1292 syscalls.
1585 1293
1586 config POSIX_TIMERS 1294 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1295 bool "Posix Clocks & timers" if EXPERT
1588 default y 1296 default y
1589 help 1297 help
1590 This includes native support for PO 1298 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1299 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1300 can be configured out to reduce the size of the kernel image.
1593 1301
1594 When this option is disabled, the f 1302 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1303 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1304 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1305 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1306 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1307 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1308
1601 If unsure say y. 1309 If unsure say y.
1602 1310
1603 config PRINTK 1311 config PRINTK
1604 default y 1312 default y
1605 bool "Enable support for printk" if E 1313 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1314 select IRQ_WORK
1607 help 1315 help
1608 This option enables normal printk s 1316 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1317 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1318 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1319 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1320 strongly discouraged.
1613 1321
>> 1322 config PRINTK_NMI
>> 1323 def_bool y
>> 1324 depends on PRINTK
>> 1325 depends on HAVE_NMI
>> 1326
1614 config BUG 1327 config BUG
1615 bool "BUG() support" if EXPERT 1328 bool "BUG() support" if EXPERT
1616 default y 1329 default y
1617 help 1330 help
1618 Disabling this option eliminates su !! 1331 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p !! 1332 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou !! 1333 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no !! 1334 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. !! 1335 Just say Y.
1623 1336
1624 config ELF_CORE 1337 config ELF_CORE
1625 depends on COREDUMP 1338 depends on COREDUMP
1626 default y 1339 default y
1627 bool "Enable ELF core dumps" if EXPER 1340 bool "Enable ELF core dumps" if EXPERT
1628 help 1341 help
1629 Enable support for generating core 1342 Enable support for generating core dumps. Disabling saves about 4k.
1630 1343
1631 1344
1632 config PCSPKR_PLATFORM 1345 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1346 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1347 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1348 select I8253_LOCK
1636 default y 1349 default y
1637 help 1350 help
1638 This option allows to disable the i !! 1351 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. !! 1352 support, saving some memory.
1640 1353
1641 config BASE_SMALL !! 1354 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1355 default y
>> 1356 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1357 help
1644 Enabling this option reduces the si !! 1358 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1359 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1360 but may reduce performance.
1647 1361
1648 config FUTEX 1362 config FUTEX
1649 bool "Enable futex support" if EXPERT 1363 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1364 default y
1652 imply RT_MUTEXES 1365 imply RT_MUTEXES
1653 help 1366 help
1654 Disabling this option will cause th 1367 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1368 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1369 run glibc-based applications correctly.
1657 1370
1658 config FUTEX_PI 1371 config FUTEX_PI
1659 bool 1372 bool
1660 depends on FUTEX && RT_MUTEXES 1373 depends on FUTEX && RT_MUTEXES
1661 default y 1374 default y
1662 1375
>> 1376 config HAVE_FUTEX_CMPXCHG
>> 1377 bool
>> 1378 depends on FUTEX
>> 1379 help
>> 1380 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1381 is implemented and always working. This removes a couple of runtime
>> 1382 checks.
>> 1383
1663 config EPOLL 1384 config EPOLL
1664 bool "Enable eventpoll support" if EX 1385 bool "Enable eventpoll support" if EXPERT
1665 default y 1386 default y
1666 help 1387 help
1667 Disabling this option will cause th 1388 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1389 support for epoll family of system calls.
1669 1390
1670 config SIGNALFD 1391 config SIGNALFD
1671 bool "Enable signalfd() system call" 1392 bool "Enable signalfd() system call" if EXPERT
1672 default y 1393 default y
1673 help 1394 help
1674 Enable the signalfd() system call t 1395 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1396 on a file descriptor.
1676 1397
1677 If unsure, say Y. 1398 If unsure, say Y.
1678 1399
1679 config TIMERFD 1400 config TIMERFD
1680 bool "Enable timerfd() system call" i 1401 bool "Enable timerfd() system call" if EXPERT
1681 default y 1402 default y
1682 help 1403 help
1683 Enable the timerfd() system call th 1404 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1405 events on a file descriptor.
1685 1406
1686 If unsure, say Y. 1407 If unsure, say Y.
1687 1408
1688 config EVENTFD 1409 config EVENTFD
1689 bool "Enable eventfd() system call" i 1410 bool "Enable eventfd() system call" if EXPERT
1690 default y 1411 default y
1691 help 1412 help
1692 Enable the eventfd() system call th 1413 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1414 kernel notification (ie. KAIO) or userspace notifications.
1694 1415
1695 If unsure, say Y. 1416 If unsure, say Y.
1696 1417
1697 config SHMEM 1418 config SHMEM
1698 bool "Use full shmem filesystem" if E 1419 bool "Use full shmem filesystem" if EXPERT
1699 default y 1420 default y
1700 depends on MMU 1421 depends on MMU
1701 help 1422 help
1702 The shmem is an internal filesystem 1423 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1424 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1425 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1426 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1427 which may be appropriate on small systems without swap.
1707 1428
1708 config AIO 1429 config AIO
1709 bool "Enable AIO support" if EXPERT 1430 bool "Enable AIO support" if EXPERT
1710 default y 1431 default y
1711 help 1432 help
1712 This option enables POSIX asynchron 1433 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1434 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1435 this option saves about 7k.
1715 1436
1716 config IO_URING 1437 config IO_URING
1717 bool "Enable IO uring support" if EXP 1438 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ !! 1439 select ANON_INODES
1719 default y 1440 default y
1720 help 1441 help
1721 This option enables support for the 1442 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1443 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1444 completion rings that are shared between the kernel and application.
1724 1445
1725 config GCOV_PROFILE_URING <<
1726 bool "Enable GCOV profiling on the io <<
1727 depends on GCOV_KERNEL <<
1728 help <<
1729 Enable GCOV profiling on the io_uri <<
1730 code coverage testing. <<
1731 <<
1732 If unsure, say N. <<
1733 <<
1734 Note that this will have a negative <<
1735 the io_uring subsystem, hence this <<
1736 specific test purposes. <<
1737 <<
1738 config ADVISE_SYSCALLS 1446 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1447 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1448 default y
1741 help 1449 help
1742 This option enables the madvise and 1450 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1451 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1452 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1453 applications use these syscalls, you can disable this option to save
1746 space. 1454 space.
1747 1455
1748 config MEMBARRIER 1456 config MEMBARRIER
1749 bool "Enable membarrier() system call 1457 bool "Enable membarrier() system call" if EXPERT
1750 default y 1458 default y
1751 help 1459 help
1752 Enable the membarrier() system call 1460 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1461 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1462 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1463 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1464 compiler barrier.
1757 1465
1758 If unsure, say Y. 1466 If unsure, say Y.
1759 1467
1760 config KCMP !! 1468 config KALLSYMS
1761 bool "Enable kcmp() system call" if E !! 1469 bool "Load all symbols for debugging/ksymoops" if EXPERT
>> 1470 default y
>> 1471 help
>> 1472 Say Y here to let the kernel print out symbolic crash information and
>> 1473 symbolic stack backtraces. This increases the size of the kernel
>> 1474 somewhat, as all symbols have to be loaded into the kernel image.
>> 1475
>> 1476 config KALLSYMS_ALL
>> 1477 bool "Include all symbols in kallsyms"
>> 1478 depends on DEBUG_KERNEL && KALLSYMS
1762 help 1479 help
1763 Enable the kernel resource comparis !! 1480 Normally kallsyms only contains the symbols of functions for nicer
1764 user-space with the ability to comp !! 1481 OOPS messages and backtraces (i.e., symbols from the text and inittext
1765 share a common resource, such as a !! 1482 sections). This is sufficient for most cases. And only in very rare
1766 memory space. !! 1483 cases (e.g., when a debugger is used) all symbols are required (e.g.,
>> 1484 names of variables from the data sections, etc).
>> 1485
>> 1486 This option makes sure that all symbols are loaded into the kernel
>> 1487 image (i.e., symbols from all sections) in cost of increased kernel
>> 1488 size (depending on the kernel configuration, it may be 300KiB or
>> 1489 something like this).
1767 1490
1768 If unsure, say N. !! 1491 Say N unless you really need all symbols.
>> 1492
>> 1493 config KALLSYMS_ABSOLUTE_PERCPU
>> 1494 bool
>> 1495 depends on KALLSYMS
>> 1496 default X86_64 && SMP
>> 1497
>> 1498 config KALLSYMS_BASE_RELATIVE
>> 1499 bool
>> 1500 depends on KALLSYMS
>> 1501 default !IA64
>> 1502 help
>> 1503 Instead of emitting them as absolute values in the native word size,
>> 1504 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1505 each containing a relative value in the range [base, base + U32_MAX]
>> 1506 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1507 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1508 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1509 address encountered in the image.
>> 1510
>> 1511 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1512 but more importantly, it results in entries whose values are build
>> 1513 time constants, and no relocation pass is required at runtime to fix
>> 1514 up the entries based on the runtime load address of the kernel.
>> 1515
>> 1516 # end of the "standard kernel features (expert users)" menu
>> 1517
>> 1518 # syscall, maps, verifier
>> 1519 config BPF_SYSCALL
>> 1520 bool "Enable bpf() system call"
>> 1521 select BPF
>> 1522 select IRQ_WORK
>> 1523 default n
>> 1524 help
>> 1525 Enable the bpf() system call that allows to manipulate eBPF
>> 1526 programs and maps via file descriptors.
>> 1527
>> 1528 config BPF_JIT_ALWAYS_ON
>> 1529 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1530 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1531 help
>> 1532 Enables BPF JIT and removes BPF interpreter to avoid
>> 1533 speculative execution of BPF instructions by the interpreter
>> 1534
>> 1535 config USERFAULTFD
>> 1536 bool "Enable userfaultfd() system call"
>> 1537 depends on MMU
>> 1538 help
>> 1539 Enable the userfaultfd() system call that allows to intercept and
>> 1540 handle page faults in userland.
>> 1541
>> 1542 config ARCH_HAS_MEMBARRIER_CALLBACKS
>> 1543 bool
>> 1544
>> 1545 config ARCH_HAS_MEMBARRIER_SYNC_CORE
>> 1546 bool
1769 1547
1770 config RSEQ 1548 config RSEQ
1771 bool "Enable rseq() system call" if E 1549 bool "Enable rseq() system call" if EXPERT
1772 default y 1550 default y
1773 depends on HAVE_RSEQ 1551 depends on HAVE_RSEQ
1774 select MEMBARRIER 1552 select MEMBARRIER
1775 help 1553 help
1776 Enable the restartable sequences sy 1554 Enable the restartable sequences system call. It provides a
1777 user-space cache for the current CP 1555 user-space cache for the current CPU number value, which
1778 speeds up getting the current CPU n 1556 speeds up getting the current CPU number from user-space,
1779 as well as an ABI to speed up user- 1557 as well as an ABI to speed up user-space operations on
1780 per-CPU data. 1558 per-CPU data.
1781 1559
1782 If unsure, say Y. 1560 If unsure, say Y.
1783 1561
1784 config DEBUG_RSEQ 1562 config DEBUG_RSEQ
1785 default n 1563 default n
1786 bool "Enable debugging of rseq() syst !! 1564 bool "Enabled debugging of rseq() system call" if EXPERT
1787 depends on RSEQ && DEBUG_KERNEL 1565 depends on RSEQ && DEBUG_KERNEL
1788 help 1566 help
1789 Enable extra debugging checks for t 1567 Enable extra debugging checks for the rseq system call.
1790 1568
1791 If unsure, say N. 1569 If unsure, say N.
1792 1570
1793 config CACHESTAT_SYSCALL !! 1571 config EMBEDDED
1794 bool "Enable cachestat() system call" !! 1572 bool "Embedded system"
1795 default y !! 1573 option allnoconfig_y
1796 help !! 1574 select EXPERT
1797 Enable the cachestat system call, w !! 1575 help
1798 statistics of a file (number of cac !! 1576 This option should be enabled if compiling the kernel for
1799 pages marked for writeback, (recent !! 1577 an embedded system so certain expert options are available
1800 !! 1578 for configuration.
1801 If unsure say Y here. <<
1802 <<
1803 config PC104 <<
1804 bool "PC/104 support" if EXPERT <<
1805 help <<
1806 Expose PC/104 form factor device dr <<
1807 selection and configuration. Enable <<
1808 machine has a PC/104 bus. <<
1809 <<
1810 config KALLSYMS <<
1811 bool "Load all symbols for debugging/ <<
1812 default y <<
1813 help <<
1814 Say Y here to let the kernel print <<
1815 symbolic stack backtraces. This inc <<
1816 somewhat, as all symbols have to be <<
1817 <<
1818 config KALLSYMS_SELFTEST <<
1819 bool "Test the basic functions and pe <<
1820 depends on KALLSYMS <<
1821 default n <<
1822 help <<
1823 Test the basic functions and perfor <<
1824 kallsyms_lookup_name. It also calcu <<
1825 kallsyms compression algorithm for <<
1826 <<
1827 Start self-test automatically after <<
1828 "dmesg | grep kallsyms_selftest" to <<
1829 displayed in the last line, indicat <<
1830 <<
1831 config KALLSYMS_ALL <<
1832 bool "Include all symbols in kallsyms <<
1833 depends on DEBUG_KERNEL && KALLSYMS <<
1834 help <<
1835 Normally kallsyms only contains the <<
1836 OOPS messages and backtraces (i.e., <<
1837 sections). This is sufficient for m <<
1838 enable kernel live patching, or oth <<
1839 when a debugger is used) all symbol <<
1840 variables from the data sections, e <<
1841 <<
1842 This option makes sure that all sym <<
1843 image (i.e., symbols from all secti <<
1844 size (depending on the kernel confi <<
1845 something like this). <<
1846 <<
1847 Say N unless you really need all sy <<
1848 <<
1849 config KALLSYMS_ABSOLUTE_PERCPU <<
1850 bool <<
1851 depends on KALLSYMS <<
1852 default X86_64 && SMP <<
1853 <<
1854 # end of the "standard kernel features (exper <<
1855 <<
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS <<
1857 bool <<
1858 <<
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE <<
1860 bool <<
1861 1579
1862 config HAVE_PERF_EVENTS 1580 config HAVE_PERF_EVENTS
1863 bool 1581 bool
1864 help 1582 help
1865 See tools/perf/design.txt for detai 1583 See tools/perf/design.txt for details.
1866 1584
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1585 config PERF_USE_VMALLOC
1872 bool 1586 bool
1873 help 1587 help
1874 See tools/perf/design.txt for detai 1588 See tools/perf/design.txt for details
1875 1589
>> 1590 config PC104
>> 1591 bool "PC/104 support" if EXPERT
>> 1592 help
>> 1593 Expose PC/104 form factor device drivers and options available for
>> 1594 selection and configuration. Enable this option if your target
>> 1595 machine has a PC/104 bus.
>> 1596
1876 menu "Kernel Performance Events And Counters" 1597 menu "Kernel Performance Events And Counters"
1877 1598
1878 config PERF_EVENTS 1599 config PERF_EVENTS
1879 bool "Kernel performance events and c 1600 bool "Kernel performance events and counters"
1880 default y if PROFILING 1601 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1602 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1603 select IRQ_WORK
>> 1604 select SRCU
1883 help 1605 help
1884 Enable kernel support for various p 1606 Enable kernel support for various performance events provided
1885 by software and hardware. 1607 by software and hardware.
1886 1608
1887 Software events are supported eithe 1609 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1610 use of generic tracepoints.
1889 1611
1890 Most modern CPUs support performanc 1612 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1613 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1614 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1615 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1616 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1617 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1618 used to profile the code that runs on that CPU.
1897 1619
1898 The Linux Performance Event subsyst 1620 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1621 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1622 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1623 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1624 capabilities on top of those.
1903 1625
1904 Say Y if unsure. 1626 Say Y if unsure.
1905 1627
1906 config DEBUG_PERF_USE_VMALLOC 1628 config DEBUG_PERF_USE_VMALLOC
1907 default n 1629 default n
1908 bool "Debug: use vmalloc to back perf 1630 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1631 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1632 select PERF_USE_VMALLOC
1911 help 1633 help
1912 Use vmalloc memory to back perf mma !! 1634 Use vmalloc memory to back perf mmap() buffers.
1913 1635
1914 Mostly useful for debugging the vma !! 1636 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. !! 1637 that don't require it.
1916 1638
1917 Say N if unsure. !! 1639 Say N if unsure.
1918 1640
1919 endmenu 1641 endmenu
1920 1642
>> 1643 config VM_EVENT_COUNTERS
>> 1644 default y
>> 1645 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1646 help
>> 1647 VM event counters are needed for event counts to be shown.
>> 1648 This option allows the disabling of the VM event counters
>> 1649 on EXPERT systems. /proc/vmstat will only show page counts
>> 1650 if VM event counters are disabled.
>> 1651
>> 1652 config SLUB_DEBUG
>> 1653 default y
>> 1654 bool "Enable SLUB debugging support" if EXPERT
>> 1655 depends on SLUB && SYSFS
>> 1656 help
>> 1657 SLUB has extensive debug support features. Disabling these can
>> 1658 result in significant savings in code size. This also disables
>> 1659 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1660 no support for cache validation etc.
>> 1661
>> 1662 config SLUB_MEMCG_SYSFS_ON
>> 1663 default n
>> 1664 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1665 depends on SLUB && SYSFS && MEMCG
>> 1666 help
>> 1667 SLUB creates a directory under /sys/kernel/slab for each
>> 1668 allocation cache to host info and debug files. If memory
>> 1669 cgroup is enabled, each cache can have per memory cgroup
>> 1670 caches. SLUB can create the same sysfs directories for these
>> 1671 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1672 to a very high number of debug files being created. This is
>> 1673 controlled by slub_memcg_sysfs boot parameter and this
>> 1674 config option determines the parameter's default value.
>> 1675
>> 1676 config COMPAT_BRK
>> 1677 bool "Disable heap randomization"
>> 1678 default y
>> 1679 help
>> 1680 Randomizing heap placement makes heap exploits harder, but it
>> 1681 also breaks ancient binaries (including anything libc5 based).
>> 1682 This option changes the bootup default to heap randomization
>> 1683 disabled, and can be overridden at runtime by setting
>> 1684 /proc/sys/kernel/randomize_va_space to 2.
>> 1685
>> 1686 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1687
>> 1688 choice
>> 1689 prompt "Choose SLAB allocator"
>> 1690 default SLUB
>> 1691 help
>> 1692 This option allows to select a slab allocator.
>> 1693
>> 1694 config SLAB
>> 1695 bool "SLAB"
>> 1696 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1697 help
>> 1698 The regular slab allocator that is established and known to work
>> 1699 well in all environments. It organizes cache hot objects in
>> 1700 per cpu and per node queues.
>> 1701
>> 1702 config SLUB
>> 1703 bool "SLUB (Unqueued Allocator)"
>> 1704 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1705 help
>> 1706 SLUB is a slab allocator that minimizes cache line usage
>> 1707 instead of managing queues of cached objects (SLAB approach).
>> 1708 Per cpu caching is realized using slabs of objects instead
>> 1709 of queues of objects. SLUB can use memory efficiently
>> 1710 and has enhanced diagnostics. SLUB is the default choice for
>> 1711 a slab allocator.
>> 1712
>> 1713 config SLOB
>> 1714 depends on EXPERT
>> 1715 bool "SLOB (Simple Allocator)"
>> 1716 help
>> 1717 SLOB replaces the stock allocator with a drastically simpler
>> 1718 allocator. SLOB is generally more space efficient but
>> 1719 does not perform as well on large systems.
>> 1720
>> 1721 endchoice
>> 1722
>> 1723 config SLAB_MERGE_DEFAULT
>> 1724 bool "Allow slab caches to be merged"
>> 1725 default y
>> 1726 help
>> 1727 For reduced kernel memory fragmentation, slab caches can be
>> 1728 merged when they share the same size and other characteristics.
>> 1729 This carries a risk of kernel heap overflows being able to
>> 1730 overwrite objects from merged caches (and more easily control
>> 1731 cache layout), which makes such heap attacks easier to exploit
>> 1732 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1733 can usually only damage objects in the same cache. To disable
>> 1734 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1735 command line.
>> 1736
>> 1737 config SLAB_FREELIST_RANDOM
>> 1738 default n
>> 1739 depends on SLAB || SLUB
>> 1740 bool "SLAB freelist randomization"
>> 1741 help
>> 1742 Randomizes the freelist order used on creating new pages. This
>> 1743 security feature reduces the predictability of the kernel slab
>> 1744 allocator against heap overflows.
>> 1745
>> 1746 config SLAB_FREELIST_HARDENED
>> 1747 bool "Harden slab freelist metadata"
>> 1748 depends on SLUB
>> 1749 help
>> 1750 Many kernel heap attacks try to target slab cache metadata and
>> 1751 other infrastructure. This options makes minor performance
>> 1752 sacrifies to harden the kernel slab allocator against common
>> 1753 freelist exploit methods.
>> 1754
>> 1755 config SHUFFLE_PAGE_ALLOCATOR
>> 1756 bool "Page allocator randomization"
>> 1757 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1758 help
>> 1759 Randomization of the page allocator improves the average
>> 1760 utilization of a direct-mapped memory-side-cache. See section
>> 1761 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1762 6.2a specification for an example of how a platform advertises
>> 1763 the presence of a memory-side-cache. There are also incidental
>> 1764 security benefits as it reduces the predictability of page
>> 1765 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1766 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1767 10th order of pages is selected based on cache utilization
>> 1768 benefits on x86.
>> 1769
>> 1770 While the randomization improves cache utilization it may
>> 1771 negatively impact workloads on platforms without a cache. For
>> 1772 this reason, by default, the randomization is enabled only
>> 1773 after runtime detection of a direct-mapped memory-side-cache.
>> 1774 Otherwise, the randomization may be force enabled with the
>> 1775 'page_alloc.shuffle' kernel command line parameter.
>> 1776
>> 1777 Say Y if unsure.
>> 1778
>> 1779 config SLUB_CPU_PARTIAL
>> 1780 default y
>> 1781 depends on SLUB && SMP
>> 1782 bool "SLUB per cpu partial cache"
>> 1783 help
>> 1784 Per cpu partial caches accellerate objects allocation and freeing
>> 1785 that is local to a processor at the price of more indeterminism
>> 1786 in the latency of the free. On overflow these caches will be cleared
>> 1787 which requires the taking of locks that may cause latency spikes.
>> 1788 Typically one would choose no for a realtime system.
>> 1789
>> 1790 config MMAP_ALLOW_UNINITIALIZED
>> 1791 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1792 depends on EXPERT && !MMU
>> 1793 default n
>> 1794 help
>> 1795 Normally, and according to the Linux spec, anonymous memory obtained
>> 1796 from mmap() has its contents cleared before it is passed to
>> 1797 userspace. Enabling this config option allows you to request that
>> 1798 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1799 providing a huge performance boost. If this option is not enabled,
>> 1800 then the flag will be ignored.
>> 1801
>> 1802 This is taken advantage of by uClibc's malloc(), and also by
>> 1803 ELF-FDPIC binfmt's brk and stack allocator.
>> 1804
>> 1805 Because of the obvious security issues, this option should only be
>> 1806 enabled on embedded devices where you control what is run in
>> 1807 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1808 it is normally safe to say Y here.
>> 1809
>> 1810 See Documentation/nommu-mmap.txt for more information.
>> 1811
1921 config SYSTEM_DATA_VERIFICATION 1812 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1813 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1814 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1815 select KEYS
1925 select CRYPTO 1816 select CRYPTO
1926 select CRYPTO_RSA 1817 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1818 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1819 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1820 select ASN1
1930 select OID_REGISTRY 1821 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1822 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1823 select PKCS7_MESSAGE_PARSER
1933 help 1824 help
1934 Provide PKCS#7 message verification 1825 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1826 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1827 module verification, kexec image verification and firmware blob
1937 verification. 1828 verification.
1938 1829
1939 config PROFILING 1830 config PROFILING
1940 bool "Profiling support" 1831 bool "Profiling support"
1941 help 1832 help
1942 Say Y here to enable the extended p 1833 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1834 by profilers such as OProfile.
1944 <<
1945 config RUST <<
1946 bool "Rust support" <<
1947 depends on HAVE_RUST <<
1948 depends on RUST_IS_AVAILABLE <<
1949 depends on !MODVERSIONS <<
1950 depends on !GCC_PLUGIN_RANDSTRUCT <<
1951 depends on !RANDSTRUCT <<
1952 depends on !DEBUG_INFO_BTF || PAHOLE_ <<
1953 depends on !CFI_CLANG || HAVE_CFI_ICA <<
1954 select CFI_ICALL_NORMALIZE_INTEGERS i <<
1955 depends on !CALL_PADDING || RUSTC_VER <<
1956 depends on !KASAN_SW_TAGS <<
1957 depends on !(MITIGATION_RETHUNK && KA <<
1958 help <<
1959 Enables Rust support in the kernel. <<
1960 <<
1961 This allows other Rust-related opti <<
1962 to be selected. <<
1963 <<
1964 It is also required to be able to l <<
1965 written in Rust. <<
1966 <<
1967 See Documentation/rust/ for more in <<
1968 <<
1969 If unsure, say N. <<
1970 <<
1971 config RUSTC_VERSION_TEXT <<
1972 string <<
1973 depends on RUST <<
1974 default "$(RUSTC_VERSION_TEXT)" <<
1975 help <<
1976 See `CC_VERSION_TEXT`. <<
1977 <<
1978 config BINDGEN_VERSION_TEXT <<
1979 string <<
1980 depends on RUST <<
1981 # The dummy parameter `workaround-for <<
1982 # (https://github.com/rust-lang/rust- <<
1983 # the minimum version is upgraded pas <<
1984 default "$(shell,$(BINDGEN) --version <<
1985 1835
1986 # 1836 #
1987 # Place an empty function call at each tracep 1837 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1838 # dynamically changed for a probe function.
1989 # 1839 #
1990 config TRACEPOINTS 1840 config TRACEPOINTS
1991 bool 1841 bool
1992 1842
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1843 endmenu # General setup
1996 1844
1997 source "arch/Kconfig" 1845 source "arch/Kconfig"
1998 1846
1999 config RT_MUTEXES 1847 config RT_MUTEXES
2000 bool 1848 bool
2001 default y if PREEMPT_RT <<
2002 1849
2003 config MODULE_SIG_FORMAT !! 1850 config BASE_SMALL
2004 def_bool n !! 1851 int
>> 1852 default 0 if BASE_FULL
>> 1853 default 1 if !BASE_FULL
>> 1854
>> 1855 menuconfig MODULES
>> 1856 bool "Enable loadable module support"
>> 1857 option modules
>> 1858 help
>> 1859 Kernel modules are small pieces of compiled code which can
>> 1860 be inserted in the running kernel, rather than being
>> 1861 permanently built into the kernel. You use the "modprobe"
>> 1862 tool to add (and sometimes remove) them. If you say Y here,
>> 1863 many parts of the kernel can be built as modules (by
>> 1864 answering M instead of Y where indicated): this is most
>> 1865 useful for infrequently used options which are not required
>> 1866 for booting. For more information, see the man pages for
>> 1867 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1868
>> 1869 If you say Y here, you will need to run "make
>> 1870 modules_install" to put the modules under /lib/modules/
>> 1871 where modprobe can find them (you may need to be root to do
>> 1872 this).
>> 1873
>> 1874 If unsure, say Y.
>> 1875
>> 1876 if MODULES
>> 1877
>> 1878 config MODULE_FORCE_LOAD
>> 1879 bool "Forced module loading"
>> 1880 default n
>> 1881 help
>> 1882 Allow loading of modules without version information (ie. modprobe
>> 1883 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1884 is usually a really bad idea.
>> 1885
>> 1886 config MODULE_UNLOAD
>> 1887 bool "Module unloading"
>> 1888 help
>> 1889 Without this option you will not be able to unload any
>> 1890 modules (note that some modules may not be unloadable
>> 1891 anyway), which makes your kernel smaller, faster
>> 1892 and simpler. If unsure, say Y.
>> 1893
>> 1894 config MODULE_FORCE_UNLOAD
>> 1895 bool "Forced module unloading"
>> 1896 depends on MODULE_UNLOAD
>> 1897 help
>> 1898 This option allows you to force a module to unload, even if the
>> 1899 kernel believes it is unsafe: the kernel will remove the module
>> 1900 without waiting for anyone to stop using it (using the -f option to
>> 1901 rmmod). This is mainly for kernel developers and desperate users.
>> 1902 If unsure, say N.
>> 1903
>> 1904 config MODVERSIONS
>> 1905 bool "Module versioning support"
>> 1906 help
>> 1907 Usually, you have to use modules compiled with your kernel.
>> 1908 Saying Y here makes it sometimes possible to use modules
>> 1909 compiled for different kernels, by adding enough information
>> 1910 to the modules to (hopefully) spot any changes which would
>> 1911 make them incompatible with the kernel you are running. If
>> 1912 unsure, say N.
>> 1913
>> 1914 config MODULE_REL_CRCS
>> 1915 bool
>> 1916 depends on MODVERSIONS
>> 1917
>> 1918 config MODULE_SRCVERSION_ALL
>> 1919 bool "Source checksum for all modules"
>> 1920 help
>> 1921 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 1922 field inserted into their modinfo section, which contains a
>> 1923 sum of the source files which made it. This helps maintainers
>> 1924 see exactly which source was used to build a module (since
>> 1925 others sometimes change the module source without updating
>> 1926 the version). With this option, such a "srcversion" field
>> 1927 will be created for all modules. If unsure, say N.
>> 1928
>> 1929 config MODULE_SIG
>> 1930 bool "Module signature verification"
>> 1931 depends on MODULES
2005 select SYSTEM_DATA_VERIFICATION 1932 select SYSTEM_DATA_VERIFICATION
>> 1933 help
>> 1934 Check modules for valid signatures upon load: the signature
>> 1935 is simply appended to the module. For more information see
>> 1936 <file:Documentation/admin-guide/module-signing.rst>.
>> 1937
>> 1938 Note that this option adds the OpenSSL development packages as a
>> 1939 kernel build dependency so that the signing tool can use its crypto
>> 1940 library.
>> 1941
>> 1942 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 1943 module DOES NOT get stripped after being signed. This includes the
>> 1944 debuginfo strip done by some packagers (such as rpmbuild) and
>> 1945 inclusion into an initramfs that wants the module size reduced.
>> 1946
>> 1947 config MODULE_SIG_FORCE
>> 1948 bool "Require modules to be validly signed"
>> 1949 depends on MODULE_SIG
>> 1950 help
>> 1951 Reject unsigned modules or signed modules for which we don't have a
>> 1952 key. Without this, such modules will simply taint the kernel.
>> 1953
>> 1954 config MODULE_SIG_ALL
>> 1955 bool "Automatically sign all modules"
>> 1956 default y
>> 1957 depends on MODULE_SIG
>> 1958 help
>> 1959 Sign all modules during make modules_install. Without this option,
>> 1960 modules must be signed manually, using the scripts/sign-file tool.
>> 1961
>> 1962 comment "Do not forget to sign required modules with scripts/sign-file"
>> 1963 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 1964
>> 1965 choice
>> 1966 prompt "Which hash algorithm should modules be signed with?"
>> 1967 depends on MODULE_SIG
>> 1968 help
>> 1969 This determines which sort of hashing algorithm will be used during
>> 1970 signature generation. This algorithm _must_ be built into the kernel
>> 1971 directly so that signature verification can take place. It is not
>> 1972 possible to load a signed module containing the algorithm to check
>> 1973 the signature on that module.
>> 1974
>> 1975 config MODULE_SIG_SHA1
>> 1976 bool "Sign modules with SHA-1"
>> 1977 select CRYPTO_SHA1
>> 1978
>> 1979 config MODULE_SIG_SHA224
>> 1980 bool "Sign modules with SHA-224"
>> 1981 select CRYPTO_SHA256
>> 1982
>> 1983 config MODULE_SIG_SHA256
>> 1984 bool "Sign modules with SHA-256"
>> 1985 select CRYPTO_SHA256
>> 1986
>> 1987 config MODULE_SIG_SHA384
>> 1988 bool "Sign modules with SHA-384"
>> 1989 select CRYPTO_SHA512
>> 1990
>> 1991 config MODULE_SIG_SHA512
>> 1992 bool "Sign modules with SHA-512"
>> 1993 select CRYPTO_SHA512
>> 1994
>> 1995 endchoice
>> 1996
>> 1997 config MODULE_SIG_HASH
>> 1998 string
>> 1999 depends on MODULE_SIG
>> 2000 default "sha1" if MODULE_SIG_SHA1
>> 2001 default "sha224" if MODULE_SIG_SHA224
>> 2002 default "sha256" if MODULE_SIG_SHA256
>> 2003 default "sha384" if MODULE_SIG_SHA384
>> 2004 default "sha512" if MODULE_SIG_SHA512
>> 2005
>> 2006 config MODULE_COMPRESS
>> 2007 bool "Compress modules on installation"
>> 2008 depends on MODULES
>> 2009 help
>> 2010
>> 2011 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2012 xz depending on "Compression algorithm" below.
>> 2013
>> 2014 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2015
>> 2016 Out-of-tree kernel modules installed using Kbuild will also be
>> 2017 compressed upon installation.
2006 2018
2007 source "kernel/module/Kconfig" !! 2019 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2020 to compress the whole initrd or initramfs instead.
>> 2021
>> 2022 Note: This is fully compatible with signed modules.
>> 2023
>> 2024 If in doubt, say N.
>> 2025
>> 2026 choice
>> 2027 prompt "Compression algorithm"
>> 2028 depends on MODULE_COMPRESS
>> 2029 default MODULE_COMPRESS_GZIP
>> 2030 help
>> 2031 This determines which sort of compression will be used during
>> 2032 'make modules_install'.
>> 2033
>> 2034 GZIP (default) and XZ are supported.
>> 2035
>> 2036 config MODULE_COMPRESS_GZIP
>> 2037 bool "GZIP"
>> 2038
>> 2039 config MODULE_COMPRESS_XZ
>> 2040 bool "XZ"
>> 2041
>> 2042 endchoice
>> 2043
>> 2044 config TRIM_UNUSED_KSYMS
>> 2045 bool "Trim unused exported kernel symbols"
>> 2046 depends on MODULES && !UNUSED_SYMBOLS
>> 2047 help
>> 2048 The kernel and some modules make many symbols available for
>> 2049 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2050 on the set of modules being selected in your kernel configuration,
>> 2051 many of those exported symbols might never be used.
>> 2052
>> 2053 This option allows for unused exported symbols to be dropped from
>> 2054 the build. In turn, this provides the compiler more opportunities
>> 2055 (especially when using LTO) for optimizing the code and reducing
>> 2056 binary size. This might have some security advantages as well.
>> 2057
>> 2058 If unsure, or if you need to build out-of-tree modules, say N.
>> 2059
>> 2060 endif # MODULES
>> 2061
>> 2062 config MODULES_TREE_LOOKUP
>> 2063 def_bool y
>> 2064 depends on PERF_EVENTS || TRACING
2008 2065
2009 config INIT_ALL_POSSIBLE 2066 config INIT_ALL_POSSIBLE
2010 bool 2067 bool
2011 help 2068 help
2012 Back when each arch used to define 2069 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2070 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2071 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2072 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2073 and have several arch maintainers pursuing me down dark alleys.
2017 2074
2018 source "block/Kconfig" 2075 source "block/Kconfig"
2019 2076
2020 config PREEMPT_NOTIFIERS 2077 config PREEMPT_NOTIFIERS
2021 bool 2078 bool
2022 2079
2023 config PADATA 2080 config PADATA
2024 depends on SMP 2081 depends on SMP
2025 bool 2082 bool
2026 2083
2027 config ASN1 2084 config ASN1
2028 tristate 2085 tristate
2029 help 2086 help
2030 Build a simple ASN.1 grammar compil 2087 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2088 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2089 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2090 functions to call on what tags.
2034 2091
2035 source "kernel/Kconfig.locks" 2092 source "kernel/Kconfig.locks"
2036 <<
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE <<
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool <<
2042 2093
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2094 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2095 bool
2045 2096
2046 # It may be useful for an architecture to ove 2097 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2098 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2099 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2100 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2101 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2102 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2103 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2104 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2105 def_bool n
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.